随机密码生成

import java.util.Random;  
  
public class RandomPassword {  
    private int length = 8;     // password length  

    private int numLen = 2;     // count of numbers  

    private int nonABNumLen = 1;// count of special character  

  
    /** 
     * get an alphabeta 
     * @return 
     */  
    private char getAB() {  
        Random rand = new Random();  
        int ri = rand.nextInt(52);  
        char c = 0;  
        if (ri < 26) {  
            c = (char) (65 + ri);  
        } else {  
            c = (char) (97 + ri - 26);  
        }  
        return c;  
    }  
  
    /** 
     * get a num 
     * @return 
     */  
    private char getNum() {  
        Random rand = new Random();  
        int ri = rand.nextInt(10);  
        char c = (char) (48 + ri);  
        return c;  
    }  
  
    /** 
     * get a non num / non abc char 
     * @return 
     */  
    private char getNonABNum() {  
        Random rand = new Random();  
        int total = (47 - 32) + (64 - 57) + (96 - 90) + (126 - 122);    //total nonABNUM characters  

        int ri = rand.nextInt(total);  
        char c = 0;   
        if (ri < (47 - 32)) {  
            c = (char) (ri + 32 + 1);   
        } else if (ri < (47 - 32)+(64 - 57)) {  
            c = (char) (ri - (47 - 32) + 57 + 1);   
        } else if (ri < (47 - 32)+(64 - 57) + (96 - 90)) {  
            c = (char) (ri - (47 - 32) -(64 - 57) + 90 + 1 );  
        } else {  
            c = (char) (ri - (47 - 32) -(64 - 57) - (96 - 90) + 122 + 1 );  
        }  
        return c;  
    }  
  
    /** 
     * Generate the password chars array 
     */  
    public String password() {  
        char[] pwd = new char[length];  
          
        // generate the pwd chars  

        for (int i = 0; i < length; i++ ) {   
            if (i < length -numLen -nonABNumLen) {  
                pwd[i] = getAB();   
            } else if (i < length -nonABNumLen ) {  
                pwd[i] = getNum();   
            } else {  
                pwd[i] = getNonABNum();   
            }  
        }  
          
        // randomly shuffle pwd char array - Fisher–Yates shuffle  

        Random rand = new Random();  
        for (int i = length - 1; i > 0; i --) {   
            int j = rand.nextInt(i + 1);  
            // swap char[i] and char[j]  

            char c = pwd[j];  
            pwd[j] = pwd[i];   
            pwd[i] = c;   
        }  
        return new String(pwd);  
    }  
      
    /** 
     * Test 
     * @param args 
     */  
    public static void main(String[] args) {  
        RandomPassword rp = new RandomPassword ();  
        for (int i = 0; i< 20; i++) {  
            System.out.println ("Random Password: " + rp.password());  
        }  
    }  
}  

某次运行结果：

Random Password: "f1iiu9E  
Random Password: X:9LT9UX  
Random Password: BO7CQ'U4  
Random Password: Esp^N00r  
Random Password: f51BpT^D  
Random Password: d2)mRPy0  
Random Password: m0Ww^8aa  
Random Password: FwV)RQ22  
Random Password: 1_9hRtSt  
Random Password: Q9m1YMM=  
Random Password: 7cN#Jo7o  
Random Password: 3oa7s^OO  
Random Password: i(OB6Xz8  
Random Password: VL6h2z^j  
Random Password: (eVqu9p9  
Random Password: ~DGGS80o  
Random Password: [2lp4xlL  
Random Password: #vs0sHv9  
Random Password: Lp0XX2]L  
Random Password: (POo9jC7